language: fix typos Change-Id: Ie1634d06461490ffc12ddf38f86135a68dfac2a9 Reviewed-on: https://go-review.googlesource.com/46851 Run-TryBot: Marcel van Lohuizen <mpvl@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Matt Layher <mdlayher@gmail.com> Reviewed-by: Nigel Tao <nigeltao@golang.org>